The invention relates in general to a turbomachine rotor, and more particularly to a fan rotor comprising a disk with slots in its periphery and respective blades attached to said rotor, each blade having a blade root engaged in a corresponding slot. The invention relates to an improvement of an elongate spacer that is interposed between the blade root and the bottom of the slot. The invention applies particularly to mounting blades made of 3D-woven composite material, of the kind that are being used more and more in fans. The invention relates to a spacer that is well adapted to this type of blade (although not exclusively so), the spacer itself possibly being made of a material that is the same or similar. One of the objects of the invention is to improve the behavior of the blades of a rotor, in particular a fan rotor, in the event of a serious incident, e.g. as a result of ingesting a bird.
It is known to insert a deformable spacer in each slot of the rotor disk between the bottom of the slot and the inwardly-facing face of the blade root retained in said slot. For example, French patent No. 2 841 609 illustrates a spacer comprising metal portions and portions made of semi-rigid elastomer. The shape of that spacer serves to accommodate movements of the root of a blade on the occurrence of an above-mentioned critical event. Under such circumstances, the fan blade pivots under the impact, with the blade root consequently pivoting in the slot in the disk. In addition to being subjected to a pivoting movement, the blade is also subjected to a plunging movement forwards and then rearwards, as a reaction. The front, central, and rear portions of the blade are subjected to twisting movements and to axial plunging movements of differing amplitudes for each of the portions.
When a blade is made of a composite material comprising a weave that is woven in three dimensions (referred to below as “3D woven”) such impacts run the risk of the blade root cracking and can lead to it breaking, and consequently to the complete loss of the fan blade.
The invention proposes a novel type of spacer of shape that is defined to reduce the impact in the event of contact between the blade and the slot, to absorb a portion of the energy generated by the impact, and to reduce the risk of the blade being damaged.